DESCRIPTION: The long term objective of the program is to obtain a detailed understanding of the functioning of the three human embryonic hemoglobins and in so doing to gain an insight into the normal behavior of the oxygen transport system which operates at the earliest stages of human development. These data will provide valuable parameters relating to the physiology and development of the early human individual. Human embryonic hemoglobins will be produced in recombinant yeast expression systems without recourse to human embryonic tissues. The characteristics and control of oxygen binding to these proteins will be investigated using both equilibrium and fast kinetic measurements. The roles of particular amino acids will be studied using site directed mutagenesis. The three dimensional structures of each of the hemoglobins in both the oxygenated and deoxygenated forms will be obtained using X-ray diffraction techniques.